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JP-7856318-B2 - Image decoding method, image encoding method, and computer-readable recording medium

JP7856318B2JP 7856318 B2JP7856318 B2JP 7856318B2JP-7856318-B2

Inventors

  • リム サン チャン
  • カン ジュン ウォン
  • リ ハ ヒュン
  • ジュン ドン サン
  • コウ ヒュン サク
  • リ ジン ホ
  • キム フイ ヨン

Assignees

  • インテレクチュアル ディスカバリー カンパニー リミテッド

Dates

Publication Date
20260511
Application Date
20230808
Priority Date
20171129

Claims (8)

  1. Decode the adaptive loop filter information of the coded tree block, A block class index is assigned to the block classification unit within the aforementioned coding tree block. Based on the adaptive loop filter information and the block class index, an adaptive loop filter is applied to the samples in the coding tree block. An image decoding method, If the coding tree block is a luminance component block, the adaptive loop filter is applied using a 7x7 diamond-shaped filter. If the coding tree block is a color difference component block, the adaptive loop filter is applied using a 5x5 diamond-shaped filter. The aforementioned block class index is determined based on directional information and activity information. At least one of the directional information and the activity information is determined based on a gradient value in at least one of the vertical, horizontal, first diagonal, and second diagonal directions. The gradient value is obtained using a one-dimensional Laplacian operation on the block classification unit, The one-dimensional Laplacian operation is performed only on specific samples included in the block classification unit. The aforementioned specific sample includes only samples at even positions where both the horizontal and vertical coordinates are even, and only samples at odd positions where both the horizontal and vertical coordinates are odd. Image decoding method.
  2. If there are unavailable peripheral samples among the peripheral samples of the sample in the coding tree block to which the adaptive loop filter is applied, the adaptive loop filter is applied by padding the unavailable peripheral samples. The image decoding method according to claim 1.
  3. The filter coefficient values used in the adaptive loop filter are represented by 8 bits. The image decoding method according to claim 1.
  4. The adaptive loop filter information includes at least one piece of information selected from information on whether or not an adaptive loop filter is executed, information on filter coefficient values, and information on the number of filters. The image decoding method according to claim 1.
  5. The information regarding whether or not the adaptive loop filter is executed includes information indicating whether or not the adaptive loop filter is executed for each color component of the coding tree block. Information indicating whether to perform an adaptive loop filter on each of the aforementioned color components is entropy-decoded in units of coding tree blocks. The image decoding method according to claim 4.
  6. The information relating to the filter coefficient values includes information relating to the luminance component and information relating to the chrominance component of the coding tree block. The image decoding method according to claim 5.
  7. Assign a block class index to the block classification unit within the coding tree block. Based on the aforementioned block class index, an adaptive loop filter is applied to the samples within the coding tree block. Adaptive loop filter information is encoded for the aforementioned encoded tree block. An image encoding method, If the coding tree block is a luminance component block, the adaptive loop filter is applied using a 7x7 diamond-shaped filter. If the coding tree block is a color difference component block, the adaptive loop filter is applied using a 5x5 diamond-shaped filter. The aforementioned block class index is determined based on directional information and activity information. At least one of the directional information and the activity information is determined based on a gradient value in at least one of the vertical, horizontal, first diagonal, and second diagonal directions. The gradient value is obtained using a one-dimensional Laplacian operation on the block classification unit, The one-dimensional Laplacian operation is performed only on specific samples included in the block classification unit. The aforementioned specific sample includes only samples at even positions where both the horizontal and vertical coordinates are even, and only samples at odd positions where both the horizontal and vertical coordinates are odd. Image encoding method.
  8. A device for transmitting a bitstream, A processor configured to generate the aforementioned bitstream, A transmitting unit configured to transmit the bitstream, Equipped with, The generation of the aforementioned bitstream is Assign a block class index to the block classification unit within the coding tree block. Based on the aforementioned block class index, an adaptive loop filter is applied to the samples within the coding tree block. Adaptive loop filter information is encoded for the aforementioned encoded tree block. This includes, If the coding tree block is a luminance component block, the adaptive loop filter is applied using a 7x7 diamond-shaped filter. If the coding tree block is a color difference component block, the adaptive loop filter is applied using a 5x5 diamond-shaped filter. The aforementioned block class index is determined based on directional information and activity information. At least one of the directional information and the activity information is determined based on a gradient value in at least one of the vertical, horizontal, first diagonal, and second diagonal directions. The gradient value is obtained using a one-dimensional Laplacian operation on the block classification unit, The one-dimensional Laplacian operation is performed only on specific samples included in the block classification unit. The aforementioned specific sample includes only samples at even positions where both the horizontal and vertical coordinates are even, and only samples at odd positions where both the horizontal and vertical coordinates are odd. device.

Description

This invention relates to an image encoding/decoding method, apparatus, and recording medium for storing a bitstream. Specifically, this invention relates to an image encoding/decoding method and apparatus based on intra-loop filtering. Recently, the demand for high-resolution, high-quality images, such as HD (High Definition) and UHD (Ultra High Definition) images, has been increasing across various application fields. As image data becomes higher resolution and higher quality, the relative data volume increases compared to conventional image data. Therefore, when transmitting image data using conventional wired or wireless broadband lines, or storing it using conventional storage media, transmission and storage costs increase. To solve these problems arising from the increasing resolution and quality of image data, highly efficient image encoding/decoding technologies for images with higher resolution and image quality are required. Various image compression techniques exist, including inter-frame prediction techniques that predict pixel values contained in the current picture from previous or subsequent pictures, intra-frame prediction techniques that predict pixel values contained in the current picture using pixel information within the current picture, transformation and quantization techniques for compressing the energy of residual signals, and entropy coding techniques that assign short codes to frequently occurring values and long codes to less frequently occurring values. By utilizing these image compression techniques, image data can be effectively compressed and transmitted or stored. Deblocking filters aim to reduce blocking phenomena occurring at block boundaries by applying vertical and horizontal filtering to the block boundaries. However, a drawback of deblocking filters is that they cannot minimize distortion between the original image and the reconstructed image during block boundary filtering. Sample-adaptive offsetting is a method used to reduce ringing by comparing pixel values with adjacent pixels on a pixel-by-pixel basis, and then applying an offset to specific pixels or to pixels whose pixel values belong to a specific range. While sample-adaptive offsetting partially minimizes distortion between the original and reconstructed images using rate-distortion optimization, it has limitations in terms of distortion minimization when the difference in distortion between the original and reconstructed images is large. This is a block diagram showing the configuration of one embodiment of an encoding device to which the present invention is applied.This is a block diagram showing the configuration of one embodiment of a decoding device to which the present invention is applied.This is a schematic diagram showing the image partitioning structure when encoding and decoding an image.This is a diagram illustrating an embodiment of the in-screen prediction process.This is a diagram illustrating an embodiment of the inter-screen prediction process.This is a diagram illustrating the transformation and quantization process.This flowchart shows an image decoding method according to one embodiment of the present invention.This flowchart shows an image encoding method according to one embodiment of the present invention.This is an example of determining gradient values in the horizontal, vertical, first diagonal, and second diagonal directions.This is an example of determining gradient values in the horizontal, vertical, first diagonal, and second diagonal directions based on a secondary sample.This is an example of determining gradient values in the horizontal, vertical, first diagonal, and second diagonal directions based on a secondary sample.This is an example of determining gradient values in the horizontal, vertical, first diagonal, and second diagonal directions based on a secondary sample.This is another example of determining gradient values in the horizontal, vertical, first diagonal, and second diagonal directions based on a secondary sample.This is another example of determining gradient values in the horizontal, vertical, first diagonal, and second diagonal directions based on a secondary sample.This is another example of determining gradient values in the horizontal, vertical, first diagonal, and second diagonal directions based on a secondary sample.This is another example of determining gradient values in the horizontal, vertical, first diagonal, and second diagonal directions based on a secondary sample.This is another example of determining gradient values in the horizontal, vertical, first diagonal, and second diagonal directions based on a secondary sample.This is another example of determining gradient values in the horizontal, vertical, first diagonal, and second diagonal directions based on a secondary sample.This is an example of determining gradient values in the lateral, vertical, first diagonal, and second diagonal directions at a specific sample position according to one e